Serengeti in general is an excellent brand with an interesting history. The Agostino, in particular, are among my favorite sunglassses ever and I have a fairly large collection.Fit: These are perfect for anyone with a large head looking for a pair of aviator/navigator style glasses. They will work for others looking for an oversized look.The lenses are the real star of the show (as they should be for sunglasses). These have real glass lenses for starters. If you’ve never had sunglasses made with actual crown glass, then you are in for a treat. Glass has the best clarity/least distortion of any lens material. That isn’t an opinion, that is simply fact. It is also much harder than other lens options and thus much more difficult to scratch. The flip side of that is that they can shatter if dropped on a hard surface or if they receive a hard impact. So, these aren’t for high impact sports or riding a motorcycle. Otherwise, glass is the only material I want in my sunglasses.Serengeti lenses can be had polarized or not (I believe the Agostino now only comes in polarized options though). Their lenses manage blue light well, and each lens color is “tuned” via their Spectral Control technology. They all feature backside anti-reflective coating, which makes for a much more comfortable viewing experience. All Serengeti glasses are also photochromic - meaning they darken when exposed to sunlight. These are ALWAYS sunglasses though. Even in their lightest state, they are still a category 2-3 lens. So, the effect is subtle - don’t expect something drastic like a pair of eyeglasses with Transitions lenses that go from clear to “dark”. These start dark and get a little darker yet.As to which color you should get, that depends on your usage and preferences. Serengeti’s website does a great job of explaining what each lens color does best. The Drivers lens are really great - a rich brown with a slight rose shifted tint. They offer a lot of contrast and work in a variety of conditions. The Drivers Gold, as the name implies, is the Drivers lens with a light gold mirror effect. The view through them is essentially the same as the Drivers lens, perhaps a touch darker. The 555NM lens is also a great lens. It’s a very dark green with a hint of silver flash mirror coating. This is Serengeti’s best lens for very bright, harsh light. The Blue mirror lens is based on the 555NM lens with a blue mirror coating on the front. So the view through them is similar to the 555NM, only shifter slightly warmer by the mirror coating. Curiously, they aren’t as dark as the “regular” 555NM lens.Again, these are great sunglasses - they and Randolph are my favorite brands. It’s a shame they aren’t more widely known. However, Serengeti have been quite popular with civilian/commercial pilots for years. To that end, the seller “Flight Sunglasses” is a sure bet for authentic Serengeti glasses and great service.They do the job wellFAST SHIPPING, authentic item received. Happy with productA truly disturbing finding - I have been a longtime fan of Serengeti sunglasses, and own several pairs. Unfortunately, when ordering these through amazon, i received a FAKE. Serengeti box, case, packaging, and everything...but the sunglasses themselves were cheap plastic sunglasses without any Serengeti labelling. Didn't even match the photo! Buyers beware, and be sure to look out for fake/counterfeit sunglasses!Serengeti, una garanzia!Le migliori lenti in circolazione!!!Se lei provate non tornerete più indietro!